/**
 * @(#)Subway2.java
 * 
 * TopCoder SRM 413 DIV 2 250 Point
 * 
 * Author:     GGshiney
 * Version : 
 * Date:       2008-8-6
 */
public class Subway2 {
    public double minTime(int length, int maxAcceleration, int maxVelocity)
    {
	double halflength = (double)length /2;
	double topSpeedTime = (double)maxVelocity / (double)maxAcceleration;
	double l1 = (double)topSpeedTime * (double)topSpeedTime  * 0.5 * (double)maxAcceleration;
	double l2 = (double)length - 2 * l1;
	if(l2 >= 0)
	    return  2 * (double)topSpeedTime + l2 / (double)maxVelocity;
	else
	     return 2 * Math.sqrt(halflength * 2 / (double)maxAcceleration);
    }
    
    public static void main(String[] args) {
	Subway2 s = new Subway2();
	System.out.print(s.minTime(0, 1, 1));
    }
}
